1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus having a structure in which a developing cartridge for developing an electrostatic latent image formed on an electrophotographic photosensitive member is detachably mounted to a mounting portion.
2. Description of the Related Art
In recent years, an electrophotographic image forming apparatus such as a color laser printer is widely used. There is known a rotary development type image forming apparatus in which a plurality of developing cartridges are mounted to a rotatable rotary. The rotary is rotated to cause the developing cartridges of different colors to be successively opposed to an electrophotographic photosensitive drum, whereby developer images of different colors are formed. Then, a color image is formed on a recording medium. Examples of the electrophotographic image forming apparatus include a copying machine, a printer, and a facsimile apparatus.
There is a demand for a construction which, when replacing the developing cartridges, facilitates the operation of mounting and detaching the developing cartridges with respect to a cartridge mounting portion provided within the apparatus main body. In particular, in the rotary development type image forming apparatus, it is necessary to prevent the developing cartridges mounted to the rotary from being detached from the rotating rotary.
As a construction for preventing detachment of the cartridges from the rotating rotary, there is known a construction in which a gripper for gripping the cartridges and a cartridge lock portion are capable of interlocking (Japanese Patent Application Laid-Open No. 2003-202793).
In the above-mentioned construction, a pair of grippers are provided at the central portion in the longitudinal direction of each cartridge. The grippers are connected to lock portions protruding from both longitudinal end surfaces of the cartridge. Further, the grippers are urged longitudinally outwards.
When mounting the cartridge to the rotary, the user grips the grippers against the urging force. When the user releases the grippers, the lock portions protrude from the side surfaces of the cartridge due to the urging force. Then, the lock portions are engaged with a locking part of the rotary, whereby it is possible to lock the cartridge to the rotary.
On the other hand, when releasing the lock, the user grips the grippers. As a result, the lock portions, which have been protruding outwardly, are accommodated within the cartridge, whereby the lock of the cartridge and the rotary is released.
The above-mentioned related art technique, which can be well adapted to the image forming apparatus sizes as required at that time, has been an excellent one from the viewpoint of practical use. In recent years, however, there is a demand for a further reduction in the size of an image forming apparatus.